If you already upgraded your player and you want to enable RDS just repeat the whole upgrade:
1. Go to http://www.samsung.com/download/index.aspx?agreement=y, look for a YP-S3 without J in its name and get the latest firmware
2. unzip the file
3. check that you have a S3.ROM and NOT a S3J.ROM
4. connect your player with your PC
5. copy S3.ROM into the root-folder of your YP-S3
6. Open notepad or any other texteditor and create a file with this textYP-S3
EU EU UMS

7. save it into the root of S3
8. unplug the player
9. power on and wait until the upgrade finished